1. Field of the Invention
The invention relates to a combined service and parking brake apparatus for vehicles and a method for executing an emergency braking action by means of the parking brake apparatus in the event of a failure of the service brake of the vehicle.
2. Description of the Prior Art
A wide variety of combined service and parking brake apparatus designs are known from the prior art. A brake apparatus of this kind includes, for example, a hydraulic service brake and a mechanical parking brake (emergency brake). Recently, parking brakes are no longer mechanically actuated solely by means of a control cable, but are instead actuated by means of an electric motor mounted directly on the wheel brake. The electric motor drives a spindle unit, which mechanically sets and locks the brake unit in a parking brake position.
When placing electric motors of this kind directly next to the wheel brake, however, space problems arise because there is very little space around the wheel brake. To this end, DE 197 32 168 C1 has proposed situating an electric motor or driving a parking brake apparatus on the wheel brake, to the side of the vehicle brake housing. In this instance, a driven shaft of the electric motor extends parallel to an axle of the spindle, spaced laterally apart from it. The driven shaft of the electric motor and the spindle are connected to each other by means of a step-down transmission. This arrangement, however, has the disadvantage that space must necessarily be available to the side of the wheel brake in order for the electric motor to be placed there.